The present invention relates generally to rotating retorts utilized in retorting carbonaceous materials. More specifically, the present invention relates to seal mechanisms for sealing the rotating vessel portion of the rotating retort to the stationary retort portions.
Rotating retorts are well-known and commonly used in the recovery of hydrocarbons from carbonaceous materials such as coal, oil shale, etc. In order to handle the massive quantities of carbonaceous materials processed during hydrocarbon recovery, the rotating retort must necessarily be very large. Because of the large dimensions, sealing of the rotating vessel portion to the stationary retort portions to prevent escape of valuable hydrocarbon gases has continually posed a problem.
Typical attempts at providing a suitable seal for sealing the rotating portion to the stationary portion have included the provision of a sealing surface around the rotating vessel portion to which suitable stationary seals are sealed during rotation. Because of the large dimensions of the rotating vessel portion, it is inherently difficult and commercially unpracticable to provide a sealing surface which does not nutate or otherwise rotate unevenly during rotation of the vessel portion. It has therefore been necessary to provide a retort seal mechanism which will compensate or follow the sealing surface nutations to thereby continually seal the rotating vessel portion to the stationary retort portions.
In order to accommodate the inherent nutation of the rotating vessel sealing surface, the seal mechanism is usually placed in a housing which is flexibly attached to the stationary retort portion so that the seal housing and seals may flexibly follow nutations of the sealing surface.
Although the use of bellows or other flexible connectors has partially solved the problem of allowing the retort seals to follow nutations in the sealing surface, a problem still exists with providing an adequate means for aligning the seal assembly on the sealing surface to provide long term reliable sealing. Specifically, conventional seal assemblies include seals which not only seal to the sealing surface but also align the sealing assembly thereon. These dual purpose seals have reduced life due to the high seal bearing intensity experienced as they continually not only seal to the sealing surface but also continually shift the seal assembly in response to sealing surface nutations. The added forces which act on the seals as they are functioning as alignment bearings, results in increased wear and reduced life of the seals.
It would be desirable to provide a retort sealing mechanism where the "bearing function" of the seals is separated out to lower seal force intensity at the sealing surface to thereby extend seal life and usefulness.
It would further be desirable to provide a rotating retort seal wherein the bearings, bushings, or other means used for aligning the seals relative the sealing surface are sealed off from the retort to prevent contamination and thereby extend bearing life.